#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define endl '\n'
void solve()
{
    int N;
    cin >> N;
    double sum = 0;
    N++;
    while (--N)
    {
        sum += 1.0 / N;
    }
    printf("%.6lf", sum);
}
int main()
{
    solve();
    return 0;
}
